28071121 has 16 divisors (see below), whose sum is σ = 30968784. Its totient is φ = 25288704.

The previous prime is 28071119. The next prime is 28071187. The reversal of 28071121 is 12117082.

It can be written as a sum of positive squares in 8 ways, for example, as 1404225 + 26666896 = 1185^2 + 5164^2 .

It is a 4-Lehmer number, since φ(28071121) divides (28071121-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 28071121 - 2¹ = 28071119 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28071092 and 28071101.

It is not an unprimeable number, because it can be changed into a prime (28078121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 142395 + ... + 142591.

It is an arithmetic number, because the mean of its divisors is an integer number (1935549).

It is a Poulet number, since it divides 2^28071120-1.

Almost surely, 2^28071121 is an apocalyptic number.

It is an amenable number.

28071121 is a deficient number, since it is larger than the sum of its proper divisors (2897663).

28071121 is a wasteful number, since it uses less digits than its factorization.

28071121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420.

The product of its (nonzero) digits is 224, while the sum is 22.

The square root of 28071121 is about 5298.2186629093. The cubic root of 28071121 is about 303.9157812932.

The spelling of 28071121 in words is "twenty-eight million, seventy-one thousand, one hundred twenty-one".